bun update: get a changelog of updated packages

[mquandalle]

A lot of packages authors publish a changelog.md file describing changes in each version. It would be great to display these change descriptions when updating packages with bun update.

[Jarred-Sumner]

would be nice

[mquandalle]

Dependabot does this in their update PRs. The implementation might be useful as reference:

• Changelog Finder
• Changelog Pruner